If the frying pan was also hot, preferably it should be blowtorched and if impossible one may immerse it in a pot of boiling water. If the pan was cold and only a few drops of hot michigs splattered on it, after a thorough cleaning it is sufficient to pour boiling water from a kettle on the pan. Since the pan is presumably made from metal, the whole pan must be kashered. If the pan is Teflon coated, then many Poskim do not permit it to be kashered at all.